217 research outputs found
NLO Corrections to Deeply-Virtual Compton Scattering
We have calculated the NLO corrections to the twist-2 part of the
deeply-virtual Compton scattering amplitude. Our results for the transverse and
antisymmetric parts agree with recent calculations by Ji and Osborne and by
Belitsky and M\"uller. In addition we present NLO results for the longitudinal
part of the amplitude.Comment: 8 pages, Latex. Error in polarised gluonic coefficient in Eq.(8)
correcte
Perturbative Part of the Non-Singlet Structure Function F_2 in the Large-N_F Limit
We have calculated Wilson coefficients and anomalous dimensions
for the non-singlet part of the structure function F_2 in the large-N_F limit.
Our result agrees with exact two and three loop calculations and gives the
leading N_F dependence of the perturbative non-singlet Wilson coefficients to
all orders in .Comment: 11 pages, including one figur
Sensitivity to atypical mycobacterial antigens in patients with Crohn's disease
Twenty-two patients with Crohn's disease were investigated for the presence of delayed cutaneous reactions and precipitating antibodies to atypical mycobacterial antigens of Runyon's Groups I, II and III as well as standard PPD. The results obtained, when compared to the control groups, do not show an increased incidence of sensitivity to such antigens in patients with Crohn's disease. However, their potential relevance to the pathogenesis of this disorder remains to be determined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44374/1/10620_2005_Article_BF02236026.pd
The Status of Lattice Calculations of the Nucleon Structure Functions
We review our progress on the lattice calculation of low moments of both the
unpolarised and polarised nucleon structure functions.Comment: 6 pages, contribution to 29th International Symposium on the Theory
of Elementary Particles, Buckow, Germany, (29 August - 2 September 1995). 6
pages, Latex, requires espcrc2.sty, epsf.st
Generalized parton distributions of the pion in chiral quark models and their QCD evolution
We evaluate Generalized Parton Distributions of the pion in two chiral quark
models: the Spectral Quark Model and the Nambu-Jona-Lasinio model with a
Pauli-Villars regularization. We proceed by the evaluation of double
distributions through the use of a manifestly covariant calculation based on
the alpha representation of propagators. As a result polynomiality is
incorporated automatically and calculations become simple. In addition,
positivity and normalization constraints, sum rules and soft pion theorems are
fulfilled. We obtain explicit formulas, holding at the low-energy quark-model
scale. The expressions exhibit no factorization in the t-dependence. The QCD
evolution of those parton distributions is carried out to experimentally or
lattice accessible scales. We argue for the need of evolution by comparing the
Parton Distribution Function and the Parton Distribution Amplitude of the pion
to the available experimental and lattice data, and confirm that the
quark-model scale is low, about 320 MeV.Comment: 25 pages, 15 figures, added discussion of the end-point behavio
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